The present invention relates to a wooden building having a lower structure with decay resisting construction.
The cause of deterioration of wooden buildings are generally classified broadly into four categories, namely, weathering, abrasion, decay and damage from insects, and especially the damage by saprogenic bacteria and termites is serious.
The saprogenic bacteria grow in wood in the presence of four factors, namely, oxygen (to wit, air), water (the water content in wood favorable for the growth of said bacteria is in the range of from 25 to 200%, and the optimum content is about 80%), temperature (the temperature favorable for said growth is in the range of from 3.degree. to 45.degree. C., and the optimum temperature is in the range of from 24.degree. to 35.degree. C.), nutrient (to wit, sugar, nitrogen compound, cellulose, lignin, etc.), and want of any of these four factors renders the growth thereof impossible. On the other hand, termites eat decayed or wet wood by preference, and particularly early wood and sapwood.
Accordingly, in the case of a wooden building, the rain water infiltrated into the building due to some defect or other of the construction, the used water leaked from the kitchen, the dewdrop from the water supply or drain pipe, etc. flow down to the sill along the column, braces, etc., while, owing to absorption of water or moisture from the continuous footing, the post footing and the surface of the foundation, the framework wood like the sill, leg or column, lower part of brace, etc. and the floor framing wood like the floor post, sleeper, joist, etc. are apt to be always wet, and compared with the upper structure of the building, the damage from saprogenic bacteria and insects is serious. Therefore, for the purpose of improving the durability of a wooden building, it is most important to protect the wood parts of the lower structure of said building against saprogenic bacteria and insects.
With a view to checking the growth of saprogenic bacteria and/or termites, the process of removing the water content and nutrient from wood has hitherto been adopted, and this process is exemplified by the open-cell method, dipping method, coating method, spray method, etc. wherein the subject wood is treated with a solution of some wood preserving agent, namely, antiseptics, insecticides, termite controlling agent, etc. However, said open-cell method and dipping method require large-scale equipment and are expensive so that they are inappropriate for use on the spot of construction, while as for said coating method and spray method, they are admittedly simple and handy, yet they are defective in that the effect thereof is poor in durability and, besides, they are incovenient for sufficiently performing said treatment after construction of the building.
Further, there is known a method of injecting antiseptics upon boring a hole in columns and/or sills. However, this method is defective in that not only it is impossible to replenish the antiseptics after consumption thereof but also the beauty of the building is spoiled thereby.